Intermediate Egret Research Articles

Identification of a nominate Intermediate Egret Ardea intermedia intermedia in south-western Australia

An adult Intermediate Egret in breeding plumage (pre-alternate moult) observed at Lake Joondalup, Western Australia, in January 2016 was identified as a vagrant of the Asian nominate taxon Ardea intermedia intermedia . Subspecific identification was established from the extent of black on the bill (which increased during the bird’s stay at the site, of at least 17 days), and was confirmed independently by its proportionally short and thickly tapering bill, which was found to lie outside the range of Australian A. i. plumifera from an image-based analysis of the bills of each taxon. This is the first documented record of this taxon for Australia.

Nestling Diet of Three Sympatric Egret Species: Rice Fields Support Breeding Egret Populations in Korea

The diets of the Intermediate Egret Egretta intermedia, Little Egret E. garzetta, and Cattle Egret Bubulcus ibis were examined by analyzing nestling regurgitations collected during the breeding season in 2005 at a colony in Asan, South Korea. Intermediate Egret nestlings mainly fed on insects (86.7% of total prey items), but fish were the most important group by biomass (64.3% of total biomass). Little Egret nestlings fed mainly on insects and fishes (43.4% and 33.2% of total items, respectively), and fish contributed 64.2% to the total biomass consumed. Cattle Egret chicks were mainly fed invertebrate prey (96.5% of total items), such as insects and spiders, which comprised just 64.3% of the total biomass of their diet. Loaches and aquatic insect larvae (mainly Odonata and Coleoptera) comprised a large proportion of the nestling diet of the three egret species. This suggests that all species forage primarily in rice fields, which represented the most extensive habitat surrounding the breeding colony.

DNA barcoding and phylogenetic relationships of Ardeidae (Aves: Ciconiiformes).

The avian family Ardeidae comprises long-legged freshwater and coastal birds. There has been considerable disagreement concerning the intrafamilial relationships of Ardeidae. Mitochondrial cytochrome c oxidase subunit I (COI) was used as a marker for the identification and phylogenetic analysis of avian species. In the present study, we analyzed the COI barcodes of 32 species from 17 genera belonging to the family Ardeidae. Each bird species possessed a barcode distinct from that of other bird species except for Egretta thula and E. garzetta, which shared one barcoding sequence. Kimura two-parameter distances were calculated between barcodes. The average genetic distance between species was 34-fold higher than the average genetic distance within species. Neighbor-joining and maximum likelihood methods were used to construct phylogenetic trees. Most species could be discriminated by their distinct clades in the phylogenetic tree. Both methods of phylogenetic reconstruction suggested that Zebrilus, Tigrisoma, and Cochlearius were an offshoot of the primitive herons. COI gene analysis suggested that the other herons could be divided into two clades: Botaurinae and Ardeinae. Our results support the Great Egret and Intermediate Egret being in separate genera, Casmerodius and Mesophoyx, respectively.

Biodiversity Assessment of Paddy Field Ecosystem using Birds as a Biodiversity Indicator

Biodiversity assessment is considered in making decisions concerning declaration of protected areas, management of nature reserves and assessment of the success of management decisions within a particular area. Biodiversity indicators are used as measures of biodiversity. Degree of disturbance or fragmentation of a definite habitat can be measured using specific indicator species. A variety of invertebrates and vertebrates are widely used as indicators of biodiversity. Birds are one of the best species for the national and international biodiversity schemes to be used as a biodiversity indicator. This study focused on the use of birds as an ecological indicator to assess the paddy field ecosystem. The study was carried out in a minor irrigation system in Awlegama Agrarian Service area in Wariyapola Divisional Secretariat. Bayawa was the selected tank with nearly a 38 ha of command area. A standard fixed-radius point count method with the radius set at 25 m was used to sample birds in the paddy field ecosystem. Shanon index was used to explain the results. During a single rice cycle, rice plants undergo three main phenological stages namely; vegetative, reproductive and ripening. All these stages are influenced by farming practices such as tillage, irrigation, crop establishment, agrochemical application and weeding. Different stages with different farming practices create distinct habitats for various bird species. According to the results, the highest Shanon index value (highest diversity) was recorded during the vegetative stage. Birds‟ diversity had a significant, strong (p=0.05) negative correlation with the age of the paddy. Initial land preparation and vegetative stages provide more food sources for the predatory birds who feed on worms, insects and snails; some of whom act as pests of paddy. Mixing of upper and the sub-soil layers in land preparation stages supply more feed for predatory birds. Cattle Egret, Red Wattled Lapwing, Intermediate Egrets, Indian Pond Heron, Black Necked Stroke were in abundance at land preparation and vegetative stage. Yellow crowned woodpecker and White throated munia were recorded during the later stages. A variety of management practices such as land preparation, crop establishments, irrigation, nutrient and pest management, harvesting within the paddy field facilitate to create different habitats with different eco systems and suitable food for bird species. The birds as a biodiversity indicator, symbolise the ecosystem and it reflects the existing condition of an ecosystems. A detailed study will reveal how these birds would help to manage different pests in the paddy fields to bring benefits to the farmers. Keywords: Biodiversity indicator, Ecosystem, Paddy field, Birds, Cattle Egret

Seasonal changes in the water bird community in Lake Inba: Influence of floating-leaved macrophytes on habitat selection

The abundance of the floating-leaved macrophytes, especially Trapa spp., has increased in many eutrophic lakes, butits effects on waterbirds is not clear. By covering the water surface with their floating-leaves, these macrophytes exert effects that differ from those of submerged macrophytes. In this study, we investigated seasonal changes in the species composition and habitat selection of the waterbird community in the shallow, eutrophic Lake Inba in relation to the presence/absence of native floating-leaved macrophytes (Trapa spp.). The results indicated higher abundances of the eastern spot-billed duck (Anas zonorhyncha), the little grebe (Tachybaptus ruficollis), the great egret (Egretta alba), theintermediate egret (Egretta intermedia), and the Eurasian coot (Fulica atra) in Trapa beds, whereas the great cormorant Phalacrocorax carbo was more abundant in the open water without macrophytes. Both great egrets and intermediate egrets seemed to actively choose the Trapa beds as a feeding habitat that allowed them to catch the small fish swimming beneath these plants. Eurasian coots utilized Trapa spp. as food directly, by grazing on its fruits and leaves. Little grebes selected Trapa beds for nesting, especially when their flock size was larger. Conversely, Trapa beds prevented the foraging behavior of great cormorants. In Lake Inba, with its suddenly deep shoreline and lack of shallow areas, there are few potential feeding habitats for waterbirds in the littoral zones. Therefore, Trapa beds might provide an alternative habitat for these species, thus serving as an important ecotone between terrestrial and aquatic ecosystems.

Tissue Distribution of Heavy Metals in Heron and Egret Chicks from Pyeongtaek, Korea

Iron, zinc, manganese, lead and cadmium were measured in the liver, kidney and bone of Grey Heron (Ardea cinerea), Intermediate Egret (Egretta intermedia), Little Egret (Egretta garzetta) and Black-crowned Night Herons (Nycticorax nycticorax) from Korea. Iron, zinc, manganese, lead and cadmium concentrations had species- and tissue- specific accumulation. Lead concentrations in all tissues of Black-crowned Night Heron and cadmium in kidneys of Intermediate Egret chicks were relatively higher than in other species. Iron and manganese in the liver, zinc in the bone, and lead and cadmium in the kidney were relatively higher than other tissues and these results have been reported in other birds. Lead concentrations in all species were at a level associated with acute lead poisoning and cadmium concentrations except for Grey Heron chicks were at a level associated with chronic cadmium exposure. Lead concentrations in livers and bones of heron and egret chicks were within a range considered background level (<6.00 μg/g dw). But, lead concentrations in kidneys of 12 of 37 heron and egret chicks were at concentrations associated with lethal lead poisoning (6.00-18 μg/g dw) and 7 of 37 chicks were compatible with death (>18.0 μg/g dw). For cadmium, all liver and kidney concentrations were at a level considered background for birds (<3.00 μg/g dw). Essential elements such as iron, zinc and manganese concentrations were within the range observed in other birds.

Effect of the environmental quality and food chain on trace element concentrations in Heron and Egret chicks at Pyeongtaek colony, Korea.

Trace element concentrations in the diet can affect the levels in birds. Heron and egret chicks have been recommended as useful biological indicators for monitoring trace element contamination in the aquatic ecosystem. Iron, zinc, manganese, copper, lead and cadmium concentrations were measured in the livers and stomach contents of Grey Heron (Ardea cinerea), Intermediate Egret (Egretta intermedia), Little Egret (Egretta garzetta) and Black-crowned Night Heron (Nycticorax nycticorax) chicks from Pyeongtaek colony, Korea in 2008. Iron, zinc, manganese, copper and cadmium concentrations in livers differed among four heron and egret species. Stomach content concentrations of iron, zinc, copper, lead and cadmium concentrations differed among the four species. Essential elements such as iron, zinc, manganese and copper concentrations were within the range of other heron and egret studies and these levels may be regulated by a normal homeostatic mechanism. Two of 11 (18.2%) Grey Heron and two of 10 (20.0%) Black-crowned Night Heron chicks exceeded the background lead level (<6 µg/g dw) for birds and were at a level considered lead exposed (6-30 µg/g dw). Cadmium concentrations did not exceed the background levels for wild birds. In livers of combined heron and egret chicks, lead, but not cadmium concentrations were associated with concentrations in the stomach contents. These results suggest that lead concentrations in chicks can reflect qualities of feeding area such as streams, rivers and paddy fields and chicks represent a bioindicator to evaluate lead contamination in aquatic ecosystems.

Diurnal Activity Budget and Habitat Usage of Four Ciconiiformes Species at the Annaiwilundawa Ramsar Wetland Sanctuary, Sri Lanka

Annaiwilundawa Ramsar wetland provides suitable habitats for a large number of residentand migratory bird species. Ciconiiformes of the Annaiwilundawa Ramsar wetland forms adiscernible component and hence have been identified as a potential bio-indicator group.Present study recorded the diurnal activity budgets of four Ciconiiformes species, namelyPurple Heron (Ardea purpurea), Intermediate Egret (Ardeola grayii), Indian Pond Heron(Egretta garzetta) and Little Egret (Mesophoyx intermedia) at the Annaiwilundawa Ramsarwetland once a month from December 2011 to November 2012.The day was divided in to three time periods as morning (6.15-10.15 hrs), noon (10.15-2.15hrs) and evening (2.15-6.15 hrs). Activities of the birds were categorized as feeding,locomotion, resting, preening, alert and searching. The activity of the birds and the habitat inwhich the activity occurred was recorded using focal and scan sampling methods in each timeperiod. Each bird species was observed for 30 minutes in each time period and the location ofthe observed bird species was recorded on a 1:50,000 scale topographical map of theAnnaiwilundawa. The marked points were jointed to conclude the ‘Used Area’ of the relevantspecies.All four species had significant difference in the diurnal activity budgets in each time period.Resting was the most dominant behaviour of these four species {[PurpleHeron=57.83±18.54%], [Indian Pond Heron=35.42±2.63%], [Little Egret=34.11±3.16%] and[Intermediate Egret=40.12±12.56%]}. Size of the area used by the four Ciconiiformes speciesdid not differ significantly (ANOVA, F=2.064, P≥0.1110). However, they showed significantrelationships between percentage time spent in different habitats and there availability withinthe ‘Used Area’ (Spearman correlation, Purple Heron z = 3.258, P≤0.0011; Indian PondHeron z=3.087, P≤ 0.0020; Little Egret z=1.978, P≤0.0480; Intermediate Egret z=3.335,P≤0.0008). Present study indicated that these four species of Ciconiiformes used theAnnaiwilundawa reservoir primarily for resting. Clear habitat partition and area usage wasobserved which may have allowed these four species to co-exist sympatrically at theAnnaiwilundawa Ramsar wetland.

SEROSURVEILLANCE OF AVIAN INFLUENZA VIRUS SUBTYPE H5N1 WITH HAEMAGGLUTINATION-INHIBITION ON WILD AQUATIC BIRDS IN PULAU DUA SERANG NATURAL RESERVES, BANTEN PROVINCE

Further detailed research is required to obtain deeper information on the role of wild birds on the distribution of Avian influenza in Asia. A research has been carried out on February–June 2007 focused on blood sampling (serosurveillance) of wild birds in Pulau Dua Nature Reserves (CAPD), Serang, Banten. The research is aimed to investigate the infection of AI virus sub-tye H5N1 on the studied wild birds. The blood samples were taken from studied aquatic birds, followed by HI (haemagglutination-inhibition) test. A total of 183 samples represent 7 water bird species were taken i.e Cattle egret Bubulcus ibis, Javan pond-heron Ardeola speciosa, Little egret Egretta garzetta, Intermediate egret Egretta intermedia, Black-crowned night heron Nycticorax nycticorax, Great egret Casmerodius albus and Grey heron Ardea cinerea. The result revealed that 41 (23.27%) samples showed the present of AIV antibodies serotype H5N1 which is identified as positive. Data showed 5 positive-test species, including B. ibis (29.27%), E. garzetta (29.27%), E. intermedia (4.88%), Ardeola speciosa (7.32%), and N. nycticorax (29.27%). A total of 41.46% were infected adult individual, whereas 58.54% were juveniles.

Breeding Flow Thresholds of Colonial Breeding Waterbirds in the Murray-Darling Basin, Australia

Biodiversity on floodplains is under increasing pressure as demand for water for human needs expands. Understanding how waterbirds respond to river flows feeding floodplain wetlands is critical for successful management. We analysed data on breeding by colonial breeding large waders—Eastern Great Egret Ardea modesta, Intermediate Egret Ardea intermedia, Little Egret Egretta garzetta, Nankeen Night Heron Nycticorax caledonicus, Australian White Ibis Threskiornis molucca, Glossy Ibis Plegadis falcinellus, Straw-necked Ibis Threskiornis spinicollis, and Royal Spoonbill Platalea regia—in response to river flow for three wetlands in the Murray-Darling Basin, Australia. Each wetland, which included Barmah-Millewa, the Macquarie Marshes, and Lake Merreti, has a distinctive geomorphology and hydrology. There were clear consistent thresholds of flow producing a >0.7 probability of attempted breeding by most species when a daily flow threshold was exceeded for 30–50 days. Flow characteristics were highly correlated and thresholds could also be expressed in terms of the total flow volume July–December and peak flow in September or October. Below thresholds, there was zero probability of breeding for most species. These minimum thresholds provide critical information for management of these wetlands. Our approach provides an analytical framework for estimating thresholds for other floodplains.

Intermediate Egret Ardea Intermedia in the Neretva River Valley (Croatia): Evaluation of Historical and Recent Data on its Movements

Two years after the first description of the heron species Intermediate Egret, in Manuel d'ornithologie (1840), the physician and natural historian Francesco Lanza observed several specimens of this species (under the name of Ardea egrettoides) in the valley of Neretva, just off the southern East Adriatic (Croatian) coast. Yet Lanza's observation remained unnoticed by the ornithological audience until the present day. An analysis of Lanza's description of the species, historical circumstances of this first record, as well as recent data on the appearance of this species outside its typical area of distribution speak in favour of the correct determination of specimens of this species in the valley of Neretva. Therefore, Lanza's description of Intermediate Egret in the valley of Neretva is the first record of this species in Europe. Sightings of this species outside its area of distribution confirm the existence of two distinct directions of movement: West African and Mediterranean.

Feeding activity of cattle egrets and intermediate egrets at different stages of rice culture in Korea

This study was conducted to investigate the feeding efficiency of the cattle egret (Bubulcus ibis) and the intermediate egret (Ardea intermedia) in relation to the stage of rice culture during two breeding seasons, 2006 and 2007, in Asan city, Chungcheongnam-do, South Korea. Cattle egrets caught mainly small invertebrate prey (insects and spiders, 98.4%) during all stages of rice cultivation, and had a higher prey capture rate in the plowing stage (14.98 prey/min) than in other stages (2.82-3.51 prey/min). Therefore, the biomass intake rate of cattle egrets was highest in the plowing stage. The intermediate egret captured both loaches (43.4%) and small invertebrates (50.6%). The prey capture rates of intermediate egrets increased gradually from the flooding stage (0.38 prey/min) to the planting stage (1.09 prey/min), and decreased in the growing stage (1.04 prey/min). However, intermediate egrets had the highest biomass intake rates in the plowing stage because more loaches were caught in the plowing stage (0.54 loaches/min) than other stages (0.23-0.36 loaches/min). Consequently, both intermediate egrets and cattle egrets had high energy intakes in the plowing stage and rice fields provided an important feeding habitat for both species.

Changes in populations of waterbirds on a wetland following water storage

Toombullen was an intermittently flooded wetland near the Murrumbidgee River in southern inland New South Wales. In 1980 it was converted to an off-river storage. In the decade following impoundment, waterbirds at Tombullen showed a range of responses to permanent inundation. Abundances of Australia pelican, little pied cormorant, great cormorant, yellow-billed spoonbill, black swan, grey teal, maned duck, great crested grebe, Australasian grebe, freckled duck, Eurasian coot, great egret, little egret and intermediate egret decreased. Numbers of Pacific heron and straw-necked ibis increased, while Australia darter, little black comorant, Pacific black duck, Australian white ibis and royal spoonbill did not show consistent trends in abundance. The death of permanently inundated red gums coincided with cessation of egrets breeding and enhanced breeding of Pacific herons. Permanent impoundment of water in Tombullen disadvantaged most species, did not affect a few, had positive impacts on two species of waterbird and reduced species diversity.

Hierarchical movement decisions in predators: effects of foraging experience at more than one spatial and temporal scale

Animal movements in heterogeneous environments play a crucial role in a variety of ecological processes. Although a hierarchical structure to the scale of movements has been observed in many animal species, few studies to date have revealed what causes such multi-spatial scale movements within the framework of optimal theories. Using detailed information on movement paths and prey captures by Intermediate Egrets in rice fields, this study explored the effects of individual experience at multi-temporal scales on subsequent movement parameters. The results supported three predictions based on optimal foraging theories: (1) movement distances at small and large spatial scales are determined by past foraging experiences over short (one minute) and long (seven to eight minutes) temporal scales, respectively; (2) responses to prey encounters vary between temporal scales, e.g., prey attacks in the previous one minute caused egrets to walk away (i.e., area-avoided search), whereas those in the preceding eight minutes caused egrets to stay around (i.e., area-restricted search); and (3) the probability of patch departure by flying increases with decreasing intake rates in the previous seven minutes, and the quitting intake rate is mostly lower than the long-term average, not including travel time. These results suggest that egrets make different adaptive decisions at different spatial scales: in response to a clumped prey distribution at a large spatial scale, and to a dispersed distribution or behavioral depression of prey at a small spatial scale. This study showed that the framework of optimal foraging theories is useful for comprehensively explaining the different movement modes in animals. It should also be emphasized that considering both area-avoided and restricted searches at multi-temporal scales is important for understanding movement decisions, particularly in organisms searching for hierarchically distributed resources.

MOVEMENT DECISIONS BY INTERMEDIATE EGRETS

An Intermediate Egret (Egretta intermedia) catching a tadpole in a flooded rice field in Japan. Animal movements in heterogeneous environments play a crucial role in a variety of ecological processes. But few studies have revealed what causes animals to show multispatial scale movements within the framework of optimal theories. Using detailed information on movement paths and prey captures by Intermediate Egrets in rice fields, we explored the effects of individual experience at multitemporal scales on subsequent movement parameters. A mobile GIS system (left), which consists of a portable GPS receiver, a laser rangefinder, and an electronic compass, allowed information about a target location to be recorded from a distant observation point (right). Simultaneously, we recorded the timing, duration, and type of behavior of the focal egret. This study showed that the framework of optimal foraging theories is useful for explaining comprehensively the different movement modes in animals. We also concluded that considering both area-avoided and restricted searches at multitemporal scales is important for understanding movement decisions, particularly in organisms searching for hierarchically distributed resources. The results of the study suggested that egrets make different adaptive decisions at different spatial scales. Prey attacks in the previous 1 minute caused egrets to walk away (area-avoided search, left) at a small spatial scale, whereas those in the preceding 8 minutes caused egrets to stay around (area-restricted search, right) at a large spatial scale. Also, the timing of patch departure by flying seemed to follow predictions by the marginal value theorem. These photographs illustrate the article “Hierarchical movement decisions in predators: the influence of foraging experience at more than one spatial and temporal scale” by Tatsuya Amano and Naoki Katayama, tentatively scheduled to appear in Ecology in 2009.

Breeding Season Diets of Egrets in Southeast Australia: Implications for Future Population Viability

Abstract Populations of egrets and other waterbirds in the Murray-Darling Basin of eastern Australia are declining. River regulation and increasing frequency of droughts are considered to be mainly responsible by reducing the frequency and extent of flooding to temporary wetlands. However, other changes have occurred to wetlands, such as the introduction of non-native fish, widespread severe declines in the abundance of native fish, increased salinity, sediment and nutrient concentrations, and removal of aquatic vegetation by livestock grazing. Current knowledge of the diets of egrets is inadequate for an assessment of any ecological implications arising from these changes. In this study the breeding season diets of Eastern Great Egret Ardea modesta and Intermediate Egret A. intermedia were quantified at a colony in the Murray Basin. Eastern Great Egrets depended mainly on introduced Common Carp Cyprinus carpio (94% of diet biomass), a species regarded as a severe pest of river systems and wetlands within...

A Study of Feeding Methods in Five Species of Herons and Egrets in Korea

Feeding methods of five species of herons and egrets were studied in an agricultural landscape in Asan city, Chungcheongnam-do, Korea in 2006. Grey herons primarily hunted while standing, whereas great egrets fed while walking slowly. Two smaller species, little and cattle egrets, were active foragers, feeding both while walking quickly and walking slowly. Little egrets were the only species using the foot stirring method. The medium-sized heron, intermediate egrets, foraged mainly while walking slowly or leaning. For grey herons, great egrets and little egrets, the frequency of use of different feeding methods was different between habitats: these species used the leaning method more frequently in rice fields than in reservoirs and ditches. Also, most herons (all species other than great egrets) showed seasonal changes in their feeding methods that are related to changes in habitat condition.

Foraging Habitat Preferences of Herons and Egrets

We investigated the foraging habitat preferences of herons and egrets in an agricultural area in Asan city, Chungcheongnam-do, Korea. In the study area, rice fields were the most abundant habitat type (86.8%) and total suitable feeding habitat was greater in the northern area (59.0%) than the southern area (22.5%) of the colony. Most feeding herons and egrets were located in the northern area of the colony. The number of feeding individuals in a given area was related to the available feeding area (Pearson correlation, r=0.773, p< 0.001 for field habitats; r=0.901, p< 0.001 for freshwater habitats). Feeding habitat preferences differed among species. Grey herons ( Ardea cinerea ), great egrets ( Egretta alba ), and black-crowned night herons ( Nycticorax nycticorax ) used reservoirs and ditches. However, intermediate egrets ( E. intermedia ) and cattle egrets ( Bubulcus ibis ) were dependent on rice fields. The little egret ( E. garzetta ) was a habitat generalist using all types of habitats. The two largest species, grey herons and great egrets, fed at deeper site than little egrets and foraged in deeper sites in reservoirs than in ditches ( χ 2 -test, χ 2 3=26.6 and p< 0.001 for grey herons, χ 2 3 =17.5 and p< 0.001 for great egrets). All species displayed seasonal changes in feeding habitat use and these changes were related with changes in availability of feeding habitats.

Waterbird breeding and environmental flow management in the Macquarie Marshes, arid Australia

AbstractColonial waterbirds breed in relatively few parts of Australia and the Macquarie Marshes are one of the more important wetlands for these species on the continent in terms of size of breeding colonies and frequency of breeding. Breeding data were collected for ten species of colonial waterbirds in the period 1986–2001: Little Black Cormorant Phalacrocorax sulcirostris, Little Pied Cormorant P. melanoleucos, Great Egret Ardea alba, Intermediate Egret A. intermedia, Little Egret A. garzetta, Cattle Egret A. ibis, Rufous Night Heron Nyctiorax caledonicus, Glossy Ibis Plegadis falcinellus, Straw‐necked Ibis Threskiornis spinicollis and Australian White Ibis T. molucca. Breeding of most colonial waterbirds in the Macquarie Marshes was positively related to flow in the three months before breeding and triggered when flows were usually above 200 000 Ml. Flow was also positively related to wetland area. These relationships allowed modelling of three different options for management of environmental flow, nominally an annual allocation of 125 000 Ml. Even though the Macquarie River is highly regulated, there were predicted to be major differences in breeding frequency, flow variability and wetland flooding for different options delivering environmental flows. Use of all environmental flows each year provided the least variable option while accumulating the flow in the major dam and delivering it at high thresholds provided considerably more variability for the Macquarie Marshes, increased breeding of colonial waterbirds and increased frequency of large floods. The size of a waterbird breeding event and flooding extent were still primarily affected by river flooding and diversions upstream, despite the amount of environmental flow and the predicted ecological differences among the environmental flow options. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Large Numbers of Breeding Egrets and Herons in China

We counted the heronries at two study areas in China, where important but unknown numbers breed. At Poyang Lake, within a 1,800 km2 area, we found ten heronries with Little Egret (Egretta garzetta), Intermediate Egret (Egretta intermedia), Great White Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Chinese Pond Heron (Ardeola bacchus), and Black-crowned Night Heron (Nycticorax nycticorax), and at Tai Lake we found five heronries within a 4000 km2 area. Heronry size ranged from a few hundred nests to 36,400 nests. Several heronries were located within human settlements, in contrast with the sites used in Europe and in North America, where herons tend to avoid human disturbance. An extrapolation of the mean densities observed at the two study areas, for all the zones of mainland China that are cultivated mostly with rice, provide a first estimate of a total numbers of up to some five million nests of herons and egrets, which is much higher than previously suggested for China.